Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions

To gain full access to our forums you must register; for a free account. As a registered Guest you will be able to:

Participate in over 40 different forums and search/browse from nearly 3 million posts.

OK, you asked for it.
I have a similar server room (similar to the FL server Rm that started the "War and Peace" thread). The difference is that it is in a basement and it is in upstate NY. We plan on using a Trane TWE AHU with a thermo expansion valve and TTP cond. unit with a 0F low ambient electronic head pressure control. We are putting the server cabinets up on blocks with sheet metal to create a plenum under them (there are two cabinets) and ducting about 50% of the air to the plenum. The rest of the air will be discharged behind the cabinets (the AHU return is in front of the cabinets). The fan will run continuously.
Does anyone think we need anything else. Hot gas bypass? Freezestat?
Actually the first question is what is the heat output of the servers. They are Dell rack mount with a power supply rated at 700W. I have heard 33% and 66%. There is a big difference with 22+ servers.

tpa-fl - Thankyou, Thankyou, Thankyou.
I did not find that info when I was looking through the dell site. Very useful.
We have Poweredge 2850 servers. I do not know yet if the UPS has output information (I do have heat dissipation info for them - 1708btuh X 4).
Just for kicks - 40W/SF works out to the minimum heat dissipation in my case (there is a range of min to max power use/heat dissipation). I am not going to use it but right now the user has a 5 ton air conditioner in a space with the servers and the personnel (and their work stations).

“There is usually documentation for heat dissiaption of the equipment rather than looking at the power supplies.

I have measured amps to large rectifier banks serving telcom equipment…”

Although the server manufacturer almost always publishes the rated BTU of their equipment, it also is almost always based on either the maximum, minimum, or idle operation of the equipment, and not the actual operating BTU because this is a function of the program and type of operation it is operating at. Therefore an actual measured wattage value while in “normal operation” is a better value for our design purposes.

”…I think air conditioning for server rooms should be sized based on the size of the room becuase they always seem to fit as much equipment in these rooms as they can…”

Although I could post volumes of information, case histories, and rebuttals regarding the above “opinion”, I will only say……….please, no rules of thumbs, we are all professionals here.

”…I would not be surprised if the heat from the equipment was 40W per square foot of floor space.”

I have a good Client of ours that we just installed fifteen(15) tons of refrigeration in a server room that has a floor area of 192 square feet. That works out to be approximately 193 watts per square foot. I’m sure glad that we didn’t use the above “rule of thumb” figure in our design heat load calculations.

Remember, “almost all” rules of thumbs are flawed by definition, so whenever possible, avoid them like the plague.

“I did not find that info when I was looking through the dell site. Very useful.
We have Poweredge 2850 servers. I do not know yet if the UPS has output information (I do have heat dissipation info for them - 1708btuh X 4)…”

Where did you get this “heat dissipation” information from? The factory site specifies this particular server to operate at between 809.62 and 1,342.59 BTU/Hr of sensible heat, depending on the operation it is on.

”…Just for kicks - 40W/SF works out to the minimum heat dissipation in my case (there is a range of min to max power use/heat dissipation). I am not going to use it…”

Based on the information already posted I would have to say that would be a wise idea on your part.

“…but right now the user has a 5 ton air conditioner in a space with the servers and the personnel (and their work stations).”

Like I have already posted, in order to start this project we must first generate a heat load calculation on the entire area, and only then can be start to design the HVAC system(s) for this project.

Olc, please give us as much information on the room itself, then list all heat producting equipment within the room, lights, people, work stations, copy machines, faxes, UPS equipment, and the such. Once listed we will most probably continue to ask several more questions in order to obtain all the essential information regarding the generation of this required heat load.

Lets get all the information before we start making any recommendations.......

Dear Thehumid1:

Regarding your previous post:

“…it would probably be worthwhile to at least put carpeting if not an insulated subfloor itself on top of the concrete flooring.”

Given Olc’s location of upstate NY, what would be the purpose of the carpet, or insulated sub flooring given the fact that the concrete floor would more than likely act like a heat sink for this server room?

This is why I’d like to obtain all the required information regarding this project before we start giving our friend any suggestions or recommendations that may, or may not work for or against his project in the long run.